Olive oil, compared to a saturated dietary fat, has a protective role on atherosclerosis in niacin-treated mice with metabolic syndrome

We aimed to investigate the impact of high-fat low-cholesterol diets rich in saturated fatty acids (HFLCD-SFAs), monounsaturated FAs (HFLCD-MUFAs) or MUFAs + omega-3 long-chain polyunsaturated FAs (HFLCD-PUFAs) in combination with niacin (NA) on atherosclerotic plaque characteristics in a mouse model (Lepob/obLDLR−/−) of metabolic syndrome (MetS). Compared to a low-fat low-cholesterol diet (LFLCD), HFLCDs increased body weight, triglycerides, insulin, pro-inflammatory cytokines, and circulating monocytes, contributing the HFLCD-SFAs to a predominance of a classical pro-inflammatory Ly6Chi population, whereas HFLCD-MUFAs and HFLCD-PUFAs to a non-classical patrolling Ly6Clo population. HFLCDs promoted atherosclerosis in the aortic roots of animals but the plaque size, collagen, and macrophage content were higher with the HFLCD-SFAs than with the HFLCD-MUFAs or HFLCD-PUFAs. Furthermore, HFLCD-SFAs promoted the intra-plaque accumulation of M1 macrophages, whereas HFLCD-MUFAs and HFLCD-PUFAs favoured the accumulation of M2 macrophages. These data suggest that dietary MUFAs had advantage over SFAs to prevent atherosclerotic events in the NA-treated MetS.